Wet fish pumps are utilized for pumping fish from storage receptacles, such as the hold of a ship, to spatially separated receptacles for storage or processing. In pumping fish, or other solids, it is important that the fish not be passed through the pump. Accordingly, it is known to suction the fish into a wet pump tank through an inlet and thereafter discharge the fish from the tank through a discharge by applying high pressure to the wet pump tank. The inlet to the tank and the discharge from the tank each have a valve such that when low pressure is applied to the tank the discharge valve is closed and the inlet valve is open permitting the fish to be suctioned into the tank. Once the fish are in the tank, the inlet valve is then closed, the tank pressurized and the discharge valve opened to permit the fish to be pumped from the tank.
A problem often encountered with this type of pump is that the fish get trapped in the inlet valve when the valve is closed subsequent to the fish being suctioned into the wet pump tank. When this happens, the inlet valve becomes locked in the open position, making it impossible to pressurize the tank as necessary to discharge the fish from the discharge port.
U.S. Pat. No. 4,517,099 discloses a fish pump which was designed to correct this problem. To achieve this, the '099 patent discloses locating the inlet valve to the tank above the maximum upper level of liquid that will accumulate within the tank so that the fish will not interfere with the closure of the inlet valve. However, this type of design is disadvantageous in that the fish which are initially suctioned into the tank fall a great distance to the bottom of the tank, sometimes as great as six feet, resulting in bruising of the fish.